The present invention pertains to a coated wear-resistant member, as well as a method for making a coated wear-resistant member, wherein the coating scheme is applied by physical vapor deposition (PVD). More specifically, the invention pertains to a coated wear-resistant member, as well as a method for making a coated wear-resistant member, wherein the coating scheme is applied by physical vapor deposition (PVD). The coating scheme includes a region with alternating sublayers of titanium aluminum silicon nitride and titanium aluminum nitride.
Physical Vapor Deposition (PVD) processes (often just called thin film processes) are atomistic deposition processes in which material is vaporized from a solid source and transported in the form of a vapor through a vacuum or low pressure gaseous (or plasma) environment to the substrate where it condenses. Typically, PVD processes are used to deposit films with thicknesses in the range of a few nanometers to thousands of nanometer; however they can also be used to form multilayer coatings, graded composition deposits, very thick deposits and freestanding structures. PVD processes can be used to deposit films of elements and alloys as well as compounds using reactive deposition processes. In reactive deposition processes, compounds are formed by the reaction of depositing material with the ambient gas environment such as nitrogen (e.g. titanium nitride, TiN). See Donald M. Mattox, Handbook of Physical Vapor Deposition (PVD) Processing, Society of Vacuum Coaters, Albuquerque, N. Mex. (1998), pp. 3-4.
Heretofore, coated wear-resistant members have been used in many applications wherein resistance to wear is a desirable property. Typically, a coated wear-resistant member comprises a substrate and a coating scheme on the substrate. The coating scheme may comprise a single coating layer or, in the alternative, it may comprise a plurality of coating layers. In many instances, the coating scheme provides the wear resistant property. One exemplary wear-resistant member is a coated cutting tool useful for the removal of material (e.g., metal) from a workpiece. Coated cutting tools include without limitation coated cutting inserts, coated end mills, coated drills, coated taps, and coated reamers. Metal forming is another area of use for a coated wear-resistant member. Such a coated wear component may be a coated drawing die or the like. The coated wear-resistant member has other tribological applications such as, for example, valve bodies, dies and punches.
In an application in which a coated wear-resistant member is desirable to use, it is advantageous for the coating scheme to exhibit an optimal level of hardness. In this regard, the hardness reflects the ability of the coating scheme to provide wear resistance to the coated wear-resistant member. Thus, there is a general desire to use a coating scheme that exhibits an optimal hardness wherein the coating scheme is not too brittle, but has sufficient hardness to provide wear-resistant properties. In an application in which a coated wear-resistant member is desirable to use, it is advantageous for the coating scheme to exhibit an acceptable level of adhesion to the substrate. In this regard, the ability of the coating scheme to adhere to the substrate typically results in an increase in the overall useful life of the coated wear-resistant member.
It can thus be seen that it would be desirable to provide a wear-resistant member that has a coating scheme, which exhibits a certain optimal hardness. Further, it can thus be seen that it would be desirable to provide a wear-resistant member that has a coating scheme, which exhibits an acceptable level of adhesion. It can also been that it would be desirable to provide a wear-resistant member that exhibits a certain optimal hardness in combination with an acceptable level of adhesion of the coating to the substrate. The overall goal is to provide such a coated wear-resistant member that exhibits improved performance properties in applications such as metalcutting, metal forming, and other tribological applications.